PLC

PLC stands for.........

                                   Programming Logic Controller

      

                         It is digital computer &automates electromechanical processes.Many industries are using PLC.

Design

• multiple input and multiple output
• works in high temperature range 
• immune to high electrical noise 
• program stored in its memory which is non volatile.

 

Programming languages 

1. ladder builder
2. functional block diagram
3. structured text
4. instruction list
5. sequential function chart

1. Ladder builder

 

 2. Functional block diagram

 

 3. Structured text

 

4. Instruction list

 

5. Sequential flow chart

Features

• It can operate in severe condition like (dust ,moisture,heat,cold)
• At the i/p side switches , sensors  are available to read values .
• At the o/p side motors ,hydraulic cylinder ,magnetic relays,solenoid & analog o/p are available.  

 Plc operation 

It consist of two basic part

• CPU
• input/output interface

CPU controlls all plc operation .It has three compnent:

• processor
• memory system
• power supply

"Scan Cycle"

During scan cycle,

1. plc reads /accepts the input data from field 
2. it execute program stored in memory
3. and at the o/p interface it writes the data

System scale 

means It has fixed  or variable i/o connection
so it has two types

1. Fixed (i/o are fixed in number cant change)
2. Modular /Rack (i/o connection can vary according condition)

Communication

For communication following protocol are used

• 9 pin RS232
• EIA-485
• ETHERNET modbus
• BACnet/DFI

  Software's for plc of different manufactures

• KEYENCE PLC
• RSLinks Lite
• RSLogix 500
• STEP 7 MICROWIN
• GX DEVELOPER

 

more information download here

download link 1

download link 2